Good news, bad news, on the use of antibiotics in livestock

First the good news: the FDA is now requiring prescriptions for antibiotics used in livestock. Time will tell if this has any impact on the sheer tonnage of antimicrobials used in agriculture.

As for the bad news, I’m not confident that I can do justice to this publication about “feather meal” as an avenue for antibiotic re-entry into our food supply. Here is an excerpt from the abstract:

...Following poultry slaughter, feathers are converted by rendering into feather meal and sold as fertilizer and animal feed, thereby providing a potential pathway for reentry of drugs into the human food supply. We analyzed feather meal (n = 12 samples) for 59 pharmaceuticals and personal care products (PPCPs) using EPA method 1694 employing liquid chromatography tandem mass spectrometry (LC/MS/MS). All samples tested positive and six classes of antimicrobials were detected, with a range of two to ten antimicrobials per sample. Caffeine and acetaminophen were detected in 10 of 12 samples. A number of PPCPs were determined to be heat labile during laboratory simulation of the rendering process. Growth of wild-type E. coli in MacConkey agar was inhibited by sterilized feather meal (p = 0.01) and by the antimicrobial enrofloxacin (p < 0.0001) at levels found in feather meal. Growth of a drug-resistant E. coli strain was not inhibited by sterilized feather meal or enrofloxacin. This is the first study to detect antimicrobial residues in feather meal.

Two to ten antimicrobials per sample! Concentrations high enough to inhibit growth of wild-type E. coli! I’m going to outsource my outrage to Tara Smith, who has an excellent post on this.